Fuel oil composition



States F trite atent Ufifice This invention relates to petroleum fuel oil compositions which contain a substantial proportion of residual fuel oil. This type of fuel oil may be prepared from a residue obtained from a waxy crude and it is usually necessary to dilute the residue with a gas oil in order to produce a fuel oil whose viscosity is adjusted to specification. Such fuel oils may contain both waxy materials I and asphaltenes and their pour points are often too high to permit storage and easy pumping at low temperatures. Some similar fuel oils prepared from naphthenic crudes do not present this drawback.

Many additives are known which are effective in reducing the pour points of lubricating oils and waxy gas oils, but these additives are without any noteworthy effect on the pour points of residual fuel oils, probably because the latter contain tasphaltenes which are not present in lubricants and gas oils. Residual fuels are much cheaper than lubricants and it is undesirable to increase the price, e.g. by using an expensive additive or an additive which is expensive at the working concentration. The present invention provides fuel oil compositions containing an additive which does not suffer from the above mentioned disadvantages.

According to the invention a fuel oil composition consists essentially of a small proportion of an additive dissolved in a base oil, the additive being a chlorinated mineral wax which preferably contains 260% e.g. 4- by weight of chlorine, and the base oil being a petroleum fuel oil which contains at least a substantial proportion of a distillation residue.

A suitable chlorinated mineral wax is a chlorinated microcrystalline wax. A microcrystalline wax is a petroleum wax obtained by dewaxing a vacuum residue to produce a petroleum lubricating oil known as a bright stock. As first separated the microcrystalline Wax contains a large e.g. 20% by weight, proportion of oil; this wax will hereinafter be called a bright stock slack Wax. The proportion of oil may be reduced by recrystallising the bright stock slack wax from a solvent; this recrystallised wax will hereinafter be called a single-stage, solvent-recrystallised, bright stock slack wax. Both a bright stock slack wax and a single-stage solvent-recrystallised bright stock slack wax may be chlorinated and used to prepare residual fuel oil compositions according to this invention. Other mineral waxes, e.g. those obtained from shale oils, may be used to prepare residual fuel oils according to the invention. Preferably the chlorinated wax is one prepared by reacting a mineral wax with elemental chlorine while the reaction mixture is irradiated with ultra violet light.

Preferably the fuel oil composition according to the in vention contains 0.05-l%, e.g. about 0.1-0.-3% by weight of the additive.

Residual petroleum fuel oils usually contain about 20- 80% by weight of the distillation residue which may be either a vacuum residue or an atmospheric residue and mixtures of both types of residue are sometimes used. It is also possible to include most petroleum hydrocarbon materials, e.g. residues from cracking and reforming processes, provided that the final blend has a viscosity and flash point according to specification. Often the blend contains only distillation residues and gas oil, the precise blend depending on the crude, processing details etc., but common blends are (a) about 50% (e.g., in the range of 40. 60%) by weight of vacuum residue and about 50% by weight of gas oil and (b) about 70% (e.g., in the range of 6080%) by weight of atmospheric residue and about 30% by weight of gas oil. All these residual fuel oils give satisfactory pour points where used as the base oil in compositions according to the invention.

Some examples of compositions according to the invention will now be described by way of example. All these compositions were blended from chlorinated waxes prepared from the same mineral wax. This mineral wax was a single-stage solvent-recrystallised bright stock slack wax obtained from a Middle East crude; its properties were:

Melting point c so Kinematic viscosity at 100 C cs 18.9 Oil content percent by weight" 4.8

It contained about 15% by weight of normal parafiins and about by weight of branched chain and cyclic compounds. This wax was chlorinated by reaction with elemental chlorine, the reaction mixture being irradiated with ultra violet radiation: three different reaction times w e used giving th addit o prod c Wax chlorinated to contain 4.75% of chlorine Wax chlorinated to contain 11.4% of chlorine Wax chlorinated to contain 15% of chlorine Each of these products was used as the additive to prepare three blended fuel oils.

EXAMPLE I The base oil was a mixture of 53% by weight of a Saharan vacuum residue and 47% by weight of a Middle East gas oil. The base oil had the following properties:

Six blended fuel oils were produced by adding 0.1% and 0.2% by weight of each additive to this base oil. The pour points of these compositions are given in Table I.

Table I Pour Point, C.

Dose of Additive, percent weight Additive with 4.75% 01 Additive with 11.4% G1 Additive with 15% Cl Without Additive EXAMPLE II The base oil was a mixture of 29.3% by weight Saharan vacuum residue, 22.1% Middle East vacuum residue and 48.6% of Middle East gas oil. It had the following properties:

Density at 15 C Kinematic viscosity at 20 C cs Sulphur content percent Asphaltenes content do Pour point C Six blended fuel oils were produced by adding 0.1% and 0.2% by weight of each additive to this base oil. The pour points of these compositions are given in Table II.

3 Table II I Pour Point, C.

Dose of Additive, percent weight 0.1 0.2 Additive with 4.75% Ol.- 12 -12 Additive with 11.4% 01.. 9 18 Additive with 15 01.. 12 18 Without Additive 3 EXAMPLE III The base oil was a mixture of 30% Gabon vacuum residue and 70% Gabon gas oil. It had the following and 0.2% by weight of each additive to this base oil. The pour points of these compositions are given in Table III.

Table III Pour Point, 0.

Dose of Additive, percent weight 0. 1 0.2 Additive with 4.75% 01 3 21 Additive with 11.4% C1. 6 -18 Additive with 15 Cl 3 l8 Without Additive +3 I claim:

1. A fuel oil composition which consists essentially of a small proportion of an additive dissolved in a base oil in an amount sufiicient to depress the pour point of said base oil, the additive being a chlorinated mineral wax and the base oil being a petroleum fuel oil which contains at least a substantial proportion of a distillation residue.

2. A fuel oil composition according to claim 1, in

4 which the chlorinated wax is one obtained by chlorinating a microcrystalline petroleum wax.

3. A fuel oil composition according to claim 2, in which the microcrystalline wax is a bright stock slack wax.

4. A fuel oil composition according to claim 2, in which the microcrystalline wax is a single-stage, solvent-recrystalline bright stock slack wax.

5. A fuel oil composition according to claim 1, in which the chlorinated wax contains 2-60% by weight of chlorine, based on the chlorinated wax.

6. A fuel oil composition according to claim 5, in which the chlorinated wax contains 420% by weight of chlorme.

7. A fuel oil composition according to claim 1, in which the chlorinated wax is one prepared by reacting the mineral wax with elemental chlorine while the reaction mixture is irradiated with ultra violet light.

8. A fuel oil composition according to claim 1 which contains 0.05-1% by weight of additive.

9. A fuel oil composition according to claim 8 which contains 01-03% by Weight of the additive.

10. A fuel oil composition according to claim 1, in which the base oil contains 2080% by weight of the distillation residue.

11. A fuel oil composition according to claim 10, in which the base oil is a blend of vacuum residue and gas oil.

12. A fuel oil composition according to claim 10, in which the base oil contains 40-60% by weight of vacuum residue.

13. A fuel oil composition according to claim 10, in which the base oil is a blend of atmospheric residue and gas oil.

14. A fuel oil composition according to claim 10, in which the base oil contains 80% by weight of atmospheric residue.

References Cited in the file of this patent UNITED STATES PATENTS 1,963,918 Mac Laren June 19, 1934 2,022,619 Gallsworthy Nov. 26, 1935 2,682,523 Talley et a1 June 29, 1954 

1. A FUEL OIL COMPOSITION WHICH CONSISTS ESSENTIALLY OF A SMALL PROPORTION OF AN ADDITIVE DISSOLVED IN A BASE OIL IN AN AMOUNT SUFFICIENT TO DEPRESS THE POUR POINT OF SAID BASE OIL, THE ADDITIVE BEING A CHLORINATED MINERAL WAX AND THE BASE OIL BEING A PETROLEUM FUEL OIL WHICH CONTAINS AT LEAST A SUBSTANTIAL PROPORTION OF A DISTILLATION RESIDUE. 